The Department of Justice issued new guidance Wednesday aimed at curbing harsh, discriminatory over-punishment of school discipline violations. The materials disseminated with the Department of Education aim to increase legal compliance after DOJ filed several lawsuits against cities that dole out criminal punishment to students for violations as minor as dress code violations.

“A routine school disciplinary infraction should land a student in the principal’s office, not in a police precinct,” U.S. Attorney General Eric Holder said Wednesday.

These policies have trapped students in what is known as the school-to-prison pipeline, which funnels students out of the classroom and into the criminal justice system. This pipeline has had a dramatic disproportionate impact on black students with disabilities. Fueling this trend are “zero tolerance” policies that impose harsh punishment for minor violations, and oftentimes remove school officials’ discretion. In some states such as Michigan, zero tolerance is mandated by a state law. The DOJ’s announcement is supported by reports and research that paint a picture of perverse, counter-productive school disciplinary policy:

Kids are arrested for wearing the wrong color socks and starting food fights. In Meridian, Miss., it was school officials – not police – who determined who should be arrested. Schools seeking to discipline students called the police, and police policy was to arrest all children referred to the agency, according to a Department of Justice lawsuit that was settled last March. The lawsuit called the the city’s police department a de facto “taxi service” shuttling students from school to juvenile detention centers. In Texas, another DOJ lawsuit highlighted one county’s policy of filing automatic criminal charges against students for truancy. And in Florida, Broward County agreed in November reform its policy after a spate of arrests for rule violations as minor as starting a food fight.

One in five black boys have received an out-of-school suspension, according to 2012 Department of Education data. And black students with disabilities are three times more likely to be expelled, a punishment that sets kids in zero-tolerance systems up for later criminal punishment. Other regional statistics tell a similar story. In Chicago, for example, three-fourths of kids arrested in public school were black. This disparate impact perpetuates a cycle of criminal justice over-exposure that follows many African Americans throughout their lives and yields astronomical incarceration rates.

Research suggests almost half of all black males are arrested by age 23. Years of zero tolerance and over-policing policies have manifest themselves in data: an estimated 49 percent of all young black males now enter the job market with an arrest record, as well as 44 percent of Hispanic males. These arrests not only impose obstacles to a lifetime of success; they also clog the criminal justice system. In testimony before the Senate Judiciary Committee earlier this year, a juvenile county chief judge in Georgia lamented that one-third of cases before him were students arrested not because they posed a threat, but because they “make adults mad.”

Those who have police contact early in life are more likely to commit crimes later. Several recent studies have confirmed that locking kids up not only diverts kids away from education; it also makes them more likely to commit more crimes later. In one study, students in gang-prevention programs in seven cities were followed over the course of seven years. Some students were subject to random stops by police, even when they hadn’t done anything wrong, while others were not. Those who had police contact early on committed five more delinquent acts on average, and were more likely to rationalize their behavior. Another study in Chicago found that those locked up as youths were more likely to commit crimes later, even as compared to other youths who had committed similar offenses but were not incarcerated.

More than half of youths are detained for offenses that do not threaten public safety. Data collected this summer by the National Juvenile Justice Network and Texas Public Policy Foundation found that, as of 2010, “almost 60 percent of confined youth in the U.S. (41,877) were still detained and imprisoned for offenses that do not pose substantial threats to public safety. These include misdemeanors, drug use, non-criminal or status offenses (e.g., curfew violations, truancy, running away), failure to show up for parole meetings, and breaking school rules.” The study also found that the rate of juvenile detentions had dropped significantly from an all-time high in 2000, but that policies of over-criminalizing student discipline continue to prevail.

Justice Department intervention in several notorious jurisdictions has already prompted some reform. But zero-tolerance policies remain popular. In Michigan, a student was recently arrested, expelled for 180 days, and placed on house arrest over allegations that he started a physical altercation with his teacher by grabbing a confiscated note from her hand. Months later, a judge agreed to wipe his record clean, but the district superintended lamented that she lacked the power to do anything in the interim, saying, “It is up to state policy makers to revise these zero tolerance laws, and until that happens, we will continue to follow our legal mandates as they are.”